The NWAs reveal as a group of murderers comes from Agatha Christies twist that the murderer doesnt have to be just one person. It was later adapted to a film in 1974. However, the coolest reference on this slide and indeed the whole list (and thats saying a lot for Wright films) is when Nicholas is creeping toward the NWAs clandestine castle meeting and Joyce Cooper announces that the pregnant Janet Barker who was spoken about at the first NWA meeting in the films first act has given birth to her twins. They are called Roger and Martin, a clear homage to Lethal Weapons Roger Murtagh and Martin Riggs.